Chloroplast sunscreening by protein condensates confers high-light tolerance.
basic_science · Level V
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- Record sourced from PubMed, PMID 42309053.
- Also identified by DOI 10.1016/j.cell.2026.05.042.
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Abstract
Sunlight fuels life but generates singlet oxygen (<sup>1</sup>O<sub>2</sub>), which causes photodamage and triggers signaling and antioxidative defense pathways in chloroplasts where photosynthesis takes place. How cells sense <sup>1</sup>O<sub>2</sub> and instantaneously mount photoprotection remains elusive. Here, we show that a key mediator of <sup>1</sup>O<sub>2</sub> responses, METHYLENE BLUE SENSITIVITY1 (MBS1), is conserved from plants to animals and comprises a zinc-finger (ZnF) domain flanked by intrinsically disordered regions. MBS1 plays a critical role in ¹O₂ sensing through ZnF conformational change and phase transition from liquid-like droplets to lower-dynamic condensates. These chloroplast-associated condensates under high light attenuate light penetration to shield chloroplasts from photodamage. In rice, MBS1-overexpressing lines exhibit enhanced high-light tolerance and yield in 4-year field trials. Our findings uncover a "sunscreening" mechanism via MBS1 condensates that confer chloroplast photoprotection, highlighting its value for improving rice yields in the field under high-light stress exacerbated by climate change.